In many fields that employ polymers it may be desirable to tag or mark such polymers to facilitate monitoring thereof. By the term "monitoring" is meant herein any type of tracing or tracking to determine the location or route of the polymers, and any type of determination of the concentration of the polymer at any given site, including singular or intermittent or continuous monitoring. For instance, it may be desirable to monitor water treatment polymers in water systems, particularly industrial water systems, or to monitor polymers that may be present in waste fluids before disposal, particularly industrial waste fluids, or to monitor the polymer used for down-hole oil well applications, particularly the route taken after introduction down-hole, or to monitor polymers that may be present in fluids used to wash a manufactured product, for instance a polymer-coated product, to determine the amount of polymer washed or leached therefrom. By fluids or liquids as used herein generally is meant aqueous, non-aqueous, and mixed aqueous/non-aqueous fluid systems. As seen from the above list of possible applications of polymer monitoring, the purpose of such monitoring may be to trace or track or determine the level of the polymer itself, or to trace or track or determine the level of some substance in association with the polymer, or to determine some property of the polymer or substance in association with the polymer, for instance its leachability.
Conventional techniques for monitoring polymers are generally time-consuming and labor intensive, and often require the use of bulky and/or costly equipment. Most conventional polymer analysis techniques require the preparation of calibration curves for each type of polymer employed, which is time-consuming and laborious, particularly when a large variety of polymer chemistries are being employed, and the originally prepared calibration curves lose their accuracy if the polymer structures change, for instance an acrylic acid ester mer unit being hydrolyzed to an acrylic acid mer unit. Direct methods wherein the level of functional groups present in a polymer is determined analytically are generally not practical for industrial use, particularly when it is desired to monitor a polymer on a frequent or continuous basis, or when rapid monitoring results are needed. Indirect methods of polymer monitoring may provide more rapid results using simpler techniques, but in many instances faster and/or more accurate determinations are desirable.
Polymers tagged with pendant fluorescent groups are generally easily monitored, even when present at low concentrations. Highly fluorescent molecules, that is molecules which have a fluorescent quantum efficiency, or fluorescent quantum yield, within the range of from about 0.1 to about 1.0, and a light absorbance molar extinction coefficient of at least 1,000, are typically detectable at concentration ranges of parts per million ("ppm") to parts per billion ("ppb") or even less. The incorporation of such a highly fluorescent species into a polymer in the amount of one weight percent (based on polymer actives) will permit the detection of such polymer at polymer concentration levels down to 0.1 ppm or less, provided the fluorescent quantum yield and the light absorbance molar extinction coefficient of the fluorescent tagging agent are not significantly adversely affected by its attachment to the polymer.
It would be desirable to provide a method of tagging polymers with pendant fluorescent groups by derivatization of a pre-existing polymer and hence avoid problems such as potential side-reactions or other complications that may arise in attempts to incorporate fluorescent monomer units into the polymer during synthesis of such polymer. It would be desirable to provide a method of tagging pre-existing polymers with pendant fluorescent groups so as to permit polymers that are commercially available without such tagging to be converted to tagged polymers. It would be desirable to provide such a method that minimizes the reaction steps required and minimizes the time required for the reaction. It would be desirable to provide such a method that proceeds under reaction conditions that do not have a deleterious effect on the polymer structure. It would be desirable to provide such a method that can utilize, as the agent providing the pendant fluorescent groups, inexpensive commercially available compositions. It would be desirable to provide such a method that can employ a wide variety of fluorescent derivatizing agents and hence provide tagged polymers having a wide variety of fluorescent spectra, particularly when it is desired to monitor polymers individually in situations where a plurality of polymers are present. For instance, such polymers may be tagged with distinguishable fluorescent derivatizing agents and hence each polymer may be individually monitored, or the derivatizing agent(s) may be selected so as to monitor the polymer(s) even in the presence of other fluorescent material(s). It would be desirable to provide such a method wherein a reasonably high concentration of polymer starting material may be utilized. It would be desirable to provide such a method that is not dependent on the presence of a single type of pendant group being present on the starting material polymer. It would be desirable to provide such a method that can proceed simultaneously with other post-polymerization derivatizing reactions. It would be desirable to provide polymers tagged with fluorescent groups produced by such a method. It would be desirable to provide such polymers having diverse fluorescent tags. It would be desirable to provide such polymers derivatized at reasonable cost. It would be desirable to provide such polymers having fluorescent spectra distinguishable from the spectra of the fluorescent derivatizing agents employed. These and other objects are provided by the present invention which is described in more detail below.